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Date: Tue, 27 Aug 2002 13:00:25 -0700
From: Chris Wedgwood <cw@f00f.org>
To: Thunder from the hill <thunder@lightweight.ods.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, Zheng Jian-Ming <zjm@cis.nctu.edu.tw>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: problems with changing UID/GID
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References: <20020827181207.GA8578@tapu.f00f.org> <Pine.LNX.4.44.0208271304250.3234-100000@hawkeye.luckynet.adm>
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On Tue, Aug 27, 2002 at 01:08:04PM -0600, Thunder from the hill wrote:

    And how do you protect a caller from having to wait for the lock?

You don't.  If they have to wait, then they wait.

    You'd need a lock count here, where you can only change the
    credentials when the count is zero. But when will that ever be?

It depends... for most non-threaded applications, immediately... for
threaded applications with lots of (day) disk IO, it could be
indefinite.

    And btw, the count bumping/downing does cost.

Almost immeasurable.  [sg]et[eu]id doesn't get called that often.



  --cw
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